1. Field of the Invention
The present invention relates to a controller for a printing apparatus able to simulate the operation modes of a plurality of different printing apparatus.
2. Description of Related Art
When a printing apparatus performs a printing operation in accordance with printing operation information input from a host computer or the like, it faithfully prints alphanumeric characters and the like in compliance with control codes (such as double size, line feed, and form feed) contained in the printing information. Further, in order to achieve a greater variety of printing styles, many of the latest printing apparatus have peculiar and characteristic operation modes. Such characteristic operation modes may include a high-speed mode to perform printing at a high speed and a designation mode designating a dot space and bit image. These modes are also specified by the control codes, particularly escape (ESC sequence) control codes included in the printing information.
Frequently, the control codes, such as the escape control codes, are defined differently depending on the model and manufacturer of the particular printing apparatus and, therefore, a particular printing apparatus cannot perform a normal printing operation unless the printing information is in conformity with its particular operation mode. Therefore, to correctly perform a printing operation, it becomes necessary to change the operation mode of the printing apparatus to correspond to the printing information.
In view of the necessity described above, such a printing apparatus has recently been developed which includes emulations of the operation modes of a plurality of different printing apparatus, which are stored in advance. Prior to the printing operation, the stored operation mode of one of the emulated printing apparatus is selected by an operator and printing information input into the printing apparatus is printed in accordance with the selected operation mode.
With such a printing apparatus, however, the operator is required to understand all of the differing operation modes stored in the printing apparatus and select one of the stored operation modes, thus causing concomitant disadvantages where the operation of the printing apparatus becomes complicated and an unskilled operator is liable to make a mistake in operating the printing apparatus.
Accordingly, the printing apparatus as disclosed in U.S. Pat. No. 4,968,159 to Sasaki et al, assigned to the same assignee as the present application and hereby incorporated by reference, emulates the operation modes of a plurality of printing apparatuses and, in selecting a particular operation mode, analyzes the control codes contained in a fixed quantity of printing information first input to the printing apparatus in order to automatically determine which one of the plurality of operation modes of the printing apparatus is prescribed in the printing information. There are such merits in this printing apparatus that its operation is not complicated, mishandling of it is unlikely, and even a beginner can use it easily.
Even in such a printing apparatus as described in Sasaki et al, which is provided with an automatic operation mode determination means, there is a difficulty that the operation mode cannot be determined from the fixed quantity of printing information initially input into the automatic operation mode determination means, in such a case as given below. Namely, in printing information which could correspond to one of a plurality of different operation modes, there are control codes common to various ones of the different operation modes. Hence, it sometimes occurs that only the common control codes are present in the fixed quantity of printing information input at first and the particular control codes which identify a particular operation mode are not present within the fixed quantity of printing information. Since in such a case the operation mode cannot be identified, the prior art apparatus has the disadvantage that it does not have a sufficient capability for determining the operation mode.